Bianca Mulder, Consultant at Lloyd's Register Rail Europe, gave her view on 'Noise Reducing Measures and their Influence on the Wheel-Rail System' at the Rail Technology Conferences 2008. Read the abstract of her presentation.
In the near future, the growth of freight traffic on the European rail networks will be limited by new regulations on noise emission. Since The Netherlands is a country where noise nuisance is a significant problem and further growth of freight railway traffic is almost blocked, the Dutch government has initiated and subsidised an innovation program on noise reduction (IPG). The IPG program aims to treat noise at the source.
Noise generated by rolling wheels is one of the main sources of railway noise. It is generated by the surface roughness in the contact patch between wheel and rail. This roughness induces vibrations and subsequently sound radiation from wheels and rails. Treating the source, in a technical sense, would mean reducing the roughness of both wheel and rail and/or absorbing induced vibrations before they are radiated.
Within the scope of the IPG program, Lloyd’s Register Rail has carried out a number of pilot projects, focussing on reducing noise of freight wagons. Within these pilots amongst others composite brake blocks (which smoothen wheel surfaces) and wheel absorbers are tested.
Noise measurements show that the tested measures are indeed very effective. Most promising are the composite brake blocks. Wagons fitted with these block types have proven to meet the relevant TSI noise requirements (current European legislation).
However, not only the effectiveness of noise reduction is considered. Broad insight is also gained on the impact on life cycle costs of the wagons, safety, homologation and maintenance. For instance, wheel profile measurements show that wheel wear mechanisms are changed due to the use of composite brake blocks. In the reference situation with cast iron brake blocks the main reasons for reprofiling generally are decrease of flange thickness and wheel flats. Yet, with the use of composite brake blocks, the flange thickness tends to increase and hollow wear is a frequent phenomenon. These changes have an important impact on the running behaviour of the wagons and call for a different maintenance approach.
Besides this changed profile wear, analysis of Gotcha/Quo Vadis data also shows that general wheel quality has improved with the application of composite brake blocks. Wheel surfaces are more smooth, less defects occur (like flats and crumblings) and flats are smoothened out during time.
Overall, the application of composite brake blocks has a positive effect on the rail system as a whole. Dynamic track loading will certainly decrease due to the improved wheel quality and noise is effectively reduced. If the wagon maintenance can subsequently be optimised, based on the knowledge gained with the pilot projects, composite brake blocks can be an efficient and cost effective measure to reduce railway noise!
About Bianca Mulder
Bianca Mulder is a Consultant with a MSc degree in Mechanical Engineering from the University of Twente. At Lloyd's Register Rail she is currently working on the application of noise reducing measures for freight traffic. She is also involved in the project management for admission of ERTMS on Thalys train sets, for safe running on HSL South. Furthermore, she is experienced with running gear, asset management and maintance optimisation.
Abouts Lloyd's Register Rail
Lloyd's Register Rail Ltd. is a leading organisation who provides technical consultancy and assurance services to the rail industry. Lloyd's Register Rail Europe B.V.is the competence centre for rolling stock and its interfaces.
About Rail Technology Conferences 2008
The Rail Technology Conferences 2008 took place at the Railway Museum in Utrecht on 24 and 25 June. The first day of the conference highlighted Switches and the second day focussed on properties of the wheel/rail contact at Wheel Rail Interface. More information is available at www.railtechnologyconferences.com
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Meer informatie over het Innovatieprogramma Geluid (IPG) vindt u in Infrasite Projecten